Britain’s eight million smokers have been urged to start ‘vaping’ after a government-backed report found that the electronic devices are 20 times less harmful than traditional cigarettes.

So far no electronic cigarette has been licensed by the Medicines and Healthcare products Regulatory Agency (MHRA) or the National Institute for Health and Care Excellence (Nice).

But a new report launched today by Public Health England, Kings College London and Queen Mary London, found e-cigarettes carry just five per cent of the risk of tobacco and should be widely adopted by smokers.

If every smoker in Britain switched to vaping, around 75,000 lives a year could be saved, they estimate. The experts called for e-cigarettes to be prescribed on the NHS once regulated.

Nagy Memes Szabolcz and Georgia Samuels at Vapefest, Shrewsbury

However several studies have found that the flavours used in e-cigarettes may cause respiratory problems and damage the immune system while research published on Tuesday by the University of Southern California suggested they could encourage youngsters to take up smoking.

“E-cigarettes are not completely risk free but when compared to smoking , evidence shows they carry just a fraction of the harm,” said Professor Kevin Fenton, Director of Health and Well-being, at PHE.

“We’re encouraging smokers to look at e-cigarettes as a way to help them to reduce exposure to harm from smoking.

“At the moment there are no licensed products that can be used for medicinal purposes and that’s why we are very supportive of the MRHA looking at the pathway for ensuring that there are safe and regulated e-cigarettes that can be promoted for medical purposes.

“Smoking continues to cause the greatest numbers of preventable deaths each year. Our ambition remains to see the first smoke free generation by 2025.”

“Concerns do remain as to the long-term health impact of e-cigarettes..."

Penny Woods, Chief Executive of the British Lung Foundation

E-cigarettes, officially known as electronic nicotine delivery systems (ENDS) deliver a nicotine hit but without the carcinogens associated with breathing in smoke. They are now the number one quitting aid in Britain, outranking other products like nicotine gums and patches.

The WHO report said manufacturers should be prevented from marketing e-cigarettes as "smoking cessation aids" until they provide robust scientific evidence to back the claim. A follow up report in October found most had not been scientifically tested and warned that nicotine can contribute to cardiovascular disease, neurodegeneration, and tumour growth. It concluded that ENDS posed serious threats to teenagers.

And because most e-cigarettes are manufactured by the tobacco industry the NHS could end up paying companies to clean up the health problems that they created.

However Professor Ann McNeill, of Kings College London, said e-cigarettes were significantly safer than tobacco and should be encouraged.

“We haven’t seen anyone die from e-cigarettes,” she told a briefing in London. “In my view smokers should try vaping. E-cigarettes could be a game-changer in public health.”

While the new report was broadly welcomed by anti-smoking and lung cancer charities, experts said that it was important that people should not become addicted to e-cigarettes.

“Concerns do remain as to the long-term health impact of e-cigarettes and while there is no evidence to suggest that they pose anywhere near the same dangers as smoking, we must continue to monitor this area carefully,” said Penny Woods, Chief Executive of the British Lung Foundation.

“In the meantime, we do advise that anyone using e-cigarettes to quit smoking should do so with a view to eventually quitting them too."

Deborah Arnott, chief executive of health charity ASH added: “Quitting completely will always be the best option, and regulation is essential as the market evolves to ensure smokers have access to the safest most effective products, and that uptake by never-smokers remains low.

“However, if every smoker switched overnight to electronic cigarettes many hundreds of thousands of premature deaths would be prevented in the years to come.”

Professor Linda Bauld, Cancer Research UK’s expert in cancer prevention said: “Fears that e-cigarettes have made smoking seem normal again or even led to people taking up tobacco smoking are not so far being realised based on the evidence assessed by the important independent review.

“In fact, the overall evidence points to e-cigarettes actually helping people to give up smoking tobacco.”